Assigi-tos to the north electric manu



March 18, 1924; 1,486,982

F. R. MCBERTY TELEPHONE EXCHANGE SYSTEM Filed March 15. 1920 4 Sheets-Sheet 1 Q: Q mu 1X1 easy my:

March 18 1924.

F. R. M BERTY TELEPHONE EXCHANGE SYSTEM Filed March 15. 1920 4 Sheets-Sheet 2 March 18 1 924.

' F. R. MCBERTY TELEPHONE EXCHANGE SYSTEM W 3513/ @J/to 14401;;

W w v fifi. Fi 5% in E. a W m i w W m m dw g W ERM m LE 5 RM I 4 f 1 m m kn w 1 P H 5 a m was I w f f g \E 5 ww d [*WMLH c w a m NM mg 7 M HUB N p L! MQPQN W \R l I I1 \QM m QM H; h 3 i v vl v 1. \km 3% W pl] g my kw www WE a www r l L INTI] Km wwm as h k w g p H Q March 18, 1924." I 1,486,982

' F. R. M BERTY TELEPHONE EXCHANGE SYSTEM Filed March 15 1920 4 sheet s-sheet I.

$0, 58 ws 0/? Y 1 'mv s r awvemfoz M i. W 351;; hter 440% FRANK R, MCBERTY, or semen, our", .assre-n FACTURING COIMIANY, OF GA.

TELEPHONE-EKG Application filed March 15, 1920.

To aZZ whom it may concern:

Be it known that l, FRANK ROBERT Mol'lsn'rr, a citizen oi? the United States, residing at Galion, n the county of: Crawford and State of Ohio, have invented certain new and useful Iu'iproveinents in Telephone Exchange Systems, of which the following is a speci lication.

This invention relates to telephone enchange systems and particularly to tele phone systems in which machine switching equipment is employed.

The principal objects of the invention are to provide an and reliable controlling and actuating means for machine switching equipment, and to devise a new and useful method for handling multi-ollice connec tions, such as connections between a private bra 1ch and a city exchange.

lVith these objects in view, new and useful :leatures have been embodied into a telephone system. The following are some of these features:

i icchanisins used for controlling the operation of machine switch s employed in the establisl'iment of telephone connections are dissociated from their operative relation with machine switches upon the completion of the contemplated connection. The mechanisms are preferably counting relays arranged at the central exchange to count or register impulses sent from a calling station, but the invention. is applicable to impulse producing, sending, recording or registering equipments of varied types and location.

The association 0"? the mechanisms, such as counting relays, with a connecting link is controlled by a testing means, such as a test relay, associated with a machine switch used in the establishment of connections and operated depending on the busy or idle condition of called subscribers or trunk lines. in accordance with a further feature, it the called line is found busy, the testing means actuator; apparatus for informing the callinn party oi this fact.

The advantages of the provision oi these foatures consist in the immediate detachment of the counting relays, after but not before the correct and complete operation of: the machine switches has been insured. By giving the testing naens control of the busy f-signal and the d ssociation of the counting relays, the calling party is PATENT OFFICE.

QION, G3: 19, A. CORPORATION OF OHIO.

HAN

Serial No. 365,921. I

pi'oinptl lil'fOlll'lGCl off the impossibility of obtaining the desired vconnect-ion. Still a further advantage of these arrangements resides in the simplified controlling circuits and reduced iuunber oi relays and other appa atus that result from adoption.

7 "o switches, such as an automatic trunk or line selecting switch, by means of which the calling line is extended upon the initialion oil the call, and a selector or connector switch may be restored or released to their normal inoperative condition after, and also prior to, the complete establishment of a telephone connection by these switches if, for instance, it becomes necessary to reroute a call. The means by which the restoration of the switches is controlled prior to the completion of the connection is comrnon to a plurality of lines.

The restoration of two switches, such as the above mentioned switches, is controllable at a common point, whereby all or any one oi the parties to a connection may be given control over the restoration of the con.- nection without the necessity of providing additional apparatus for this purpose, and, furthermore, the whole connection may be instantaneously annulled to give room to the establishment of a new connection.

A new and useful impulse receiving device in the form of countii'ig relays is pro vidcd. The counting relays are arranged to make possible therapid sending of impulses, the immediate setting or control of switching devices associated with the counting relays, and the consumption of a minimum amount of current during the operation of the e relays. All this is made possible due to the correlation between the various counting relays, and the correlation between the counting relays and the rest of the system.

hiloans are provided for establishing and maintaining; a connection between calling and called lines. it the called line is idle direct connection to the line is made. It it is busy, the connection is not disestablished but is simply maintained op a, preferably by a test relay As soon as the called line becomes idle, the test relay operates and completes the co nection. If the calling party does not w 1 to wait until the called lino becomes id e may operate means,

e. by hanging up his re eive", for completely restorirg the co nection.

Inter-edict such as conned tions from a private branch exchange line to a city line, are established in the following manner: First, a connection local to the calling exchange, e. g. private branch ex change, is partially established. l Vhen, in the course of the establishment of this local connection, it becomes evident that a connection with another exchange is desired, the partially established local connection is annulled. The fact that an inter-oilice and not an intra-office connection is desired is preferably dicated by the sending of local switch controlling impulses representing a digit characteristic for an inter-ofi'ice line. After the complete restoration of the local connection, another switch is operated to extend the calling line towards the called line associated with the distant exchange. The last mentioned switch is preferably so arranged that its actuation is caused by means operated in response to the iuitiation of the call, and in accordance with a further feature oi the invention, the mentioned means are brough into operative re lation with the switch at tne time of the restoration of the local connection.

Due to this method of handling multioiiice connections, the circuits and apparatus required are simplified, and iutenollice con nections are obtainable at a relatively speed, In addition to the apparatus necessary for local connections, only a few rclays, with their controlling circuits, and a line switching device need be provided for nulti-or'hce traffic. In accordance with further features of the invention, this additional device may be used for the double purpose of extending a line as a calling or called line, and the additional relays co-operate also in the establishment of purely local connections.

One of the switches used in the establishment of connections, preferably the intero-iiice connections, is a two-way switch, i. e, one operable to extend connections "from a line used as a calling line, and to this line when called. When the two-way switch is used to extend a connection from a calling line, it is automatically operated in response to the initiation of the call to connect with an idle trunk line, l i hen this switch is used as a connector to extend a connection to the mentioned line as a called line, it is open ated at the will of acallinp; party, such as an operator at the private or .it-y exchange, or subscriber.

A two-way trunk, i. one through which connections may be established in both directions, is provided. In accordance with the present exeinplification of the invention, t 18 twoway trunk cooperates with the mentioned two-way switch and is used for interconnecting two exchanges, such as a private branch exchange with a city eX change. signaling means, such as a ringing current .qeneiatoi, associated wnh the i v, rw 4 a t i two-way tiunl inis er atoi is connected to ring a line coiniected w "1e trunk, but

t 1 :1: :1 only 1.1 this line ano not ii Lb 1s a (li'zillllg ins used for nreventi venerator is actui.

ten under the co, cl? the switch, such as the twoway switch, by means a which the i hue in question is connected aith the trunk. fit testing means, such as relay oi-cleraoly ssociateo r s witch, is 0961'? too bei, Y a and l lip Q i 0,4 eas out,

advantages :1 gal TA 7 1 xi 7 will on, Of wide y o ld'tion of considerable ap cat-ed cir- W cuits, the switc cord c with the this purpose controlling rcla should be uncle; o A I;

ful means snip rious features 0 selectors may be us '1 ing such features rious other types i s l i hile in the present invention it is center p of counting relays for earn countin relays or other is registering apparatus in common tor a gnu necting circuits and as these circuits upon its line. Arrangements thi well-lrnown in the art.

These and other features of will be more readily un "f -1L followi description 0 arrangement of the ten new,

the appended cl .ns.

-u with relay in applyleft-hand heel. col 112, and the W ed battery. energi so u. to be here n? closes c' T windings and 1.0;. front coutz. groun d ed b .1 become ozr iron {1'11 1,:

cen'tet, tne 1o 1 i to groun 3' armature and i'eF-ustnncos 139 14:1 and the to ronnd;

- I slow-a. 41h rou nth tl 1e riojht-l hack contact o re. ml 14:9 the centri uings of roh -thr contact zor: rcrnstoncc is reduced to qua. L i

in a. manner to it a: other call i at this then the relay 112 being; csei qizceth the lineelay 1051 of tho rrin CSllUlQf line conr the Winding: ot the armature and front ot the linc-i'oln-y'lll of the second .ino' line. the middle becl: contact and o. oi the cut-off relay 107 of the ca ling line. the hack contact and c oi the r 11 the left-hand l "front 1 oi the relay ianc arznotnrcs and front conc ized rela s correspond hand armature of the 112. and the winding grounded battery. The energized and causes. ency another nair of relays 136 1 10. the extension ground throng 10. the le calling line to another con- It shrnild be noted at this .1 the relays 112 remain in a decondition as longas the trunks l which they are associated are idle.

oi the second Tens selection.

on the energization of the relay 112, a closed from grounded battery i the frontcontact and armature of ay, the WlDfllIlQ' of aconnecting relay v and the left-hand back contact and a mature oi? relay 1Y9 to ground. The relay becomes cner ized and operatively con .1 the norm I dissociated colouring relays 2) with the trunk A. to Which the counting relays are individual. A circuit s closed from ground through the 3s of relays 201 and 202, conductor upper ii'ront contact and armature the relay 151. relay contacts 142 and 132, conductor 106, the circuit through the call incsubstat'on. conductor 105 relay contacts 131 and 1.. and retardation coil 150 to grounded. battery. The relay 201 and, somewhat later. the sloW-tdpull-up relay h-econ energized. The relay 202 closes a circu' :rom ground through the Winding or. relay the upper bacl contact and nri'nature t a relay 204 the "front contact and armature of relay 202. conductor 156, the middle front contact and armature of and the outer front contact and of the relay 11 1 to grounded hatre j The relay becomes energized and closes locking circuit for ltselit through front contact and its iii armature, and is independent o the contacts of relays 202 and 204:. The

iducror 1,553, which circuit r uy 201 closes circuit from ground through the Windii L o relay 211. the upper h contacts and armatures of relays 210. 12. 1.14. 216. 218. 220. 222. 2241-. 226. and U1 the F ont contact and armature oi relay 2.1. the lower armature end back contact relay 208. conductor 156, the middle tront contact and armature of relay and the o ter front contact and armaot the 114 to grounded battery. The 211 becomes energized and locks 'hrouoh upper front-contact and he unper back contacts and arma- IOU the winding of Upon the rcchoeure the line-circuit, the rah 201 becomes energized and closes l. circu 219 through the upper con-- tects c relays 216-228. The relay 219 comes energized. loclrs up and opens the i the relay 2.17.

This last closure of the line-circuit is o. l duration, and the relay 20' t ItS armature. circuit- ,..nn ground through the l ay 205, the upper back conre clay 206 the upper l armature of the relay 20 the front con ..c cull armature of the relay 202, and connector 156 to grounded batery. The relay 205 becomes energized and locks up.

In its lowermost front contact and armature the relay 20o clones a circuit from ground thr ugh the Winning. f the tem group relay 190. coulluct tionerl contact of relay 20 contacts; anzl armatures or 208, and the conductor 1 0 ground battery. The relay 100 heoines an-t closes a circuit it; ll'l n'r-nlutl tln the lolll'i'll s relay 170. contact 192 of relay 190, conductor l the lowermost contact and arinature of the relay 219, and conductor 156 to grounded battery. The relay 170 hecomes energized unrl locks up through its contact 171. resistance 175, the hack contact and armature of relay 154;. and the ou er front Contact and armature of the relay 0 or 195, the menthe upper back eys 209 aucl 1 i;

to grounded battery.

and conductor 156 to grounded battery. The relay 208 becomes energmecl and closes through its upper front contact ans urinature. and conductor 156, an energizing circuit for the relay 200. The relay closes a locking; circuit for itselt through its lower front contact and armature and conductor 156. Upon the opening of the upper back contact of the relay 208, the locking circuits of the relays 216 and 219 are opened, and these relays become Clo-energized. Another circuit opened in the upper back contact or the relay 208 is the one including the tens group relay 190, whereupon this relay hecoines (lo-energized. The relay 208 becomes now {lo-energized. its circuit he p opened in contact 191 of the relay 190, but the relay 209 remains locked up.

Units selection.

The relays 201 and 202 being energized. upon the cle-energization of the relay 208 the relay 211 becomes energized by current flowing through the above traced circuit. The units digit of the called number is one, and the calling device is operated to hanc lllQll resistance winding co ii'itcrrupt the line circuit once and then throi lgh the of the 1 lower znrl the {6011* The relay its the conductor 1550.

Upon the reclosuro 01 t. relay 201 ninth somewhat l. er. t: lOQCOl '.e energized. The reluy 20 energization of the re l he m 213, and this reley opens the locking circu of the relay 211. The relay 202 closes a circuit "from ground through the winclin of; relay the upper front contncts and armaturcs oi the relays 206 and 204, the "front co; l a mature 01" relay 202 and conductor 156 to grounded battery. The relay 207 becomes encrgizerl and locks up through conductor lower front contact and arinatutz'e the relay connects conductor 156 through con-- cluotor the lower armature (l r; J contact of and the Winding or units group selecting relay to grou The relay 180 becomes energize/cl, and closes a circuit from ground through the w' ailing of the first units selecting relay 160, con tact 181 of the relay 180, conductor 188% the lowermost front contact and armature of the relay 218., and conductor 156 to grounueo. battery. The relay 160 becomes energized and locks up through its contacts 161, re sistence 165. the heel: con ct ancl armature of the relay 15%. and the front contact e115. armature of the relay 114 to grounded hattery. I

The first relay 160 and the fo th 1Y0. associated. with trunk A, being e r the selection of the callerl line N o. 4 pletetl anrl this l ne is connecttl connecting circuit 1 selected upon tn tion of the cell t "h station 100.

I ent. it)? is in ground. potenti battery t u ntacts 173, one the winding of the called cutoff relay 1017*. The cut-off 107 becomes 1 'th relay 179. The rethe cut-oil relay of the called l nc which cir- I y 1;. 4 relays l d and will,

either cl these reasons when the relays 10 l lfil 1T0 become cucrgrizzoi'l. insufficient left-hand Windluit its energizainiug de-encra not rung and is severed from the connecting cir- 'WltllCiS of relay curred, flows through the ma iutuiuei ugh contacts 182 law 11. boro 1 mixed and causes Fill the restoration uated apparatus in the above desc-i 111161. Upon the de-euergiizuliou oi the relay 112., the relay '1", lrcouies dc had and causes in relay 180 auil 2. Iii View of and 153 uot c go t connection ..or to the seizure of the called line), the more u'ior of the relay 114 results also 40 he decnero ization oi? the relays 160 and Tram the foregoing, it will be seen that the connector relays 160 and 170 are opera l ir espective of the busy or idle cond are maintained l. l? of the cal ed line opr a ol until c 0 mg; party restores the receiver to the switch hoolrv Eli thereto the cal ins: subscriber chooses to wait i l he ca led fi' beconics idle, he will 1.1 the ueutioned connection to the ca led be unable to intrude 1 line, bu will upon the cm ction already existing" With he called because his connection is ."i as my 179. H s soon as the called liuo becomes idle the relay 179 becomes eueraimed and auses the completion of the couuertiou in the above described manueh Four Wilma. of" Galli /m private brmicizone c/lmige Zinc to city Zim'.

- the same manner as or private branch exchange connection. His line is connetced with the trunk A. and the associate" counting relays. In order to obtaiconnection, the subscriber operdevice to send a group of Q1; impulse, to the counting rel ys. The counting relays operate in the above described mauue in response to the tenth interruption or" the line circuit by the sending device, the counting; relay 2255 becomes energized and loci-1s up. The encrgization of this relay results in the establishment of a path from grounded battery through" the outer ar1nature and front contact of the relay 114, the middle armature and front contact of the relay 151, conductor 156, the lowermost trout contact and armature of the relay 231, the lowermost armature and back Contact of the relay 206, conductor 115 the Winding of relay 113, and the righthaud back contact and armature of the relay 110 to ground. The relay 1113 becomes energized.

121 its middle back contact, the relay 113 ope the circuit, including relays 11 1, and in its outer right-hand back contacts, the circuit of relays 112, 130, 140, and 107 These relays become de-energized and restore the connection between the calling line and the trunk A. The de-energization of the relay 112 results in the de-energization ot the relay 151 and the subsequent disconnection of the counting relays.

Prior to the restoration of the counting relays, the last long impulse causes the tuation oi the relay 202, but due to the retarded energization of this relay the relay 113 has time to become energized, and being; itself sloW-torelease its arinatures, eri"'orms further tiiinc-tioiis to be presently described. Furthermore, under tie joint control of the relays 231 202 and 205, the relay 1% and the tenth relay 170 are energized in the above described manner. However, upon the de-euergization of the relay 1141-. all the actuated counting relays and the relays 190 and 170 are (lo-energized.

The "further functions performed by the relay 113 are follows: In its lei flhand armature and front Contact. this relay closes a circuit through the left-hand armature and back contact of the relay 110, and the winding: of relay 1.11 to ground. The relay 111 becomes energized. Another circuit closed by relay 113, extends from ground through its righhhaud inner ture and trout contact, the armature and Jack contact of relay 302, and the wlodinc; of relay 350 to grounded battery. The lay 350 becomes energized. The relay 350 closes circuits from ground through the winding Oi relay 302 the windings oil rolays 370 and 360, representing the calling: line number relay contacts 851 and 352., and

the right-hand front contacts and armatures of the relay 109 to grounded battery. The relays 302, 360 and 370 become energized. These relays are locked up through. a cir cuit including the relay contacts 361, 3'71, resistances 369, 379, and the left-hand arr-nature and back contact of relay 309 to grounded battery.

If thecity trunk with which the relay 302 is associated is busy, then the ground from the right-hand middle armature and front contact of the relay 113 is extended through the armature and front contact of the relay 302, and through the armatures and front contacts of all the relays 302 associated with busy city trunks, to the armature and back contact of an idle relay, eg. 302, and then through the winding of the associated selecting relay 350? to grounded battery. This relay operates like the relay 350 to cause the extension of thecalling line to the city trunk represented by it.

As above stated in connection with the description of theoperations performed in extending the calling line to trunk A, upon the initiation of a call and until the line is connected with the trunk, the relay 110 is energized, While this relay is energized, it maintainsopen. in its right-hand back contact the circuit of relay 113, pre venting a false operation of the latter. For the relatively short period of time that the relay 113 is energized,the relay 111 is maintained energized and prevents the energization of relay 110 and the subsequent premature deTenergization of relay 113 in response to the initiation of another call. The extension of a calling line during this period of time is delayed until the relay 113 becomes de-energized.

Another circuit, closed by relay 350 is from ground through the contacts 353 of this relay and the. winding of relay 301 to grounded battery. The relay 301 becomes energized and. closes a locking circuit for itself through its inner front contact and armature and the right-hand back contact and armature of relay 309. Upon the energization of the relay 302, the relay 350 becomes de-energized. Shortly after this, the relay 113 releases its arm-atures, and causes in turn the de energization of relay 111.

In response to the operation of the relays 360 and 370, a circuit isclosed from ground through the winding of relay 107, relay contacts 363 and 373, the high resistance righthand winding of test relay 303, to grounded battery. The relays 107 and 303 become en ergized, and the relay 303 closes a locking circuitfor these relays through its low resistance left hand winding and left-hand armature and front contact. Due to the closure vofithis vlow resistance, path, the calling line is renderedbusy as above described.

A further result of the energization of the relays 360 and 370 is the establishment of a circuit from ground through the winding of relay 311, the upper armature back contact of relay 30 1, relay contacts 374- and 3641, the loop through the calling station, relay contacts 362 and 372, the winding of slow acting relay 306, the outer left-hand armature of relay 303 to grounded ha tery. The relays 306 and 311 become one gized, and the former closes a circuit through its left-hand armature and front contact for energizing relay 307. The relay 307 locks up through its left-hand inner front contact and armature and the left-hand back con tact and armature of the relay 309.

The calling private branch exchange line is now extended to an answering jack 100, located at the city exchange operatofis posi* tion. A circuit is closed from grounded battery through the winding of relay 4:02, the upper back contact and arn'iature of relay 103, conductor 321, the winding of relay the right-hand front contact and armature of relay 30-6., conductor 3 i2, and the lower armature and back contact relay 103 to ground. The relays 323 and 402 become energized. The relay 41-02 causes the lighting of lamp 4110, whereupon the city operator in serts an answering plug 401 into the answer ing jack 4100. The relay 1:03 becomes energized and causes the de-energization of re lay 402. The relay 323 remains energized by current supplied through the repeating coil of the city operators cord circuit.

The city operator converses with the private branch exchange subscriber in the well-known manner, and completes the connection to the called line through calling plug 405 and multiple jack 4:06. The ring ing of the called station by closure of the ringing key and the operation of the supervisory apparatus at the city opera tors position is accomplished in the wellknown manner.

If at any time during conversation, the private branch operator wants to talk with either one of the subscribers, she may do so by connecting her telephone set 35?; in bridge of the conductors 321, 322 through the contacts of 324.

If the operator desires to tall: \vi'l". private branch exchange subsc iber exclusion of the city subsc i was or operator, she actuates key contacts Throue'l'i the lower contacts of an cner is closed for relay This becomes energized, opens the city side of thconnection, and connects the operators telephone set through the uppcr and middle make contacts of and conductors 321 and 322 with the private branch exchange subscribers telephone. In response to the restoration of the contacts 325, the circuit is restored to its talking condition.

The private branch exchange subscriber th 0 o the may call the branch exchange operator, if he so. desires, by moving his switch-hook up and down or by operating his dial. This inter? ipts inomei'itarily the energizing circuit of relays 311 and 306, as described above. The slow-acting relay 306 does not release its arniatures, but relay 311 responds to the interruptions of the circuit. A circuit is closed from ground through the armature and bacli' contact of relay 311, Winding oi? relay 308. outer left-hand armature and trout contart o1 relay 307, to grounded battery the contacts of key The relay 303 is energized and locks up tln'ough its inner armature and front contact. The relay 308 closes a circuit from battery, contarts o'l key 325, outer armature and trout contact oi? relay 308, call lamp 0, front contact and inner armature oi relay 308 to ground. The lamp 330 is lighted, indicating to the private branch exchange operator that a party using the trunk associated with the call lan'ip desires to converse with her. By means of key 324:, she connects here telephone set 355 to conductors 321, as above described. When disconnection is desired and the 'alling party restores his receiver to the switch hook, the relays 311 and 306 become deenergizcd. The relay 300 closes a circuit from grounded battery through its lett-hand armature and back contact, the right-hand ari'i'iature and front contact of relay 307 and. the slow acting relay 309 to ground. The relay 309 opens its back contacts, whereupon the relays 301, 302, 307, 360 and 370 become ale-energized. Upon the de-energization of relay 307, the relays 308 and 300 become tie-energized, and upon the de-energization of relays 360 and 370 the relays 107 and becoine de-energized.

The city operator receives the clearingout signal in the well-known manner, and restores the calling side oi": the connection.

R'mtcnsimt of call from city exchange to pmwuc Mano/z. median-g0 substation.

The subscriber at station B, desiring a connection, causes the lighting of lamp 411, whereupon the city operator extends his line through jack 407, plug 401. plug 105 and incl: 4.3" to cmiductors 321, 322. The city operator artuates her ringing key 420, and the al u'nating current relay 323, bridged across these trunk conductors responds to the ringing current, and connects grounded battery through the leit-hand outer armalure and back contact of relay 303, the ar mature and front contact 01"" the relay 323, and the winding of slow acting relay 312 to ground. The relay 312 becoines energlued and closes a circuit from grounded battery through its lower armature and front contact, the lamp 330, and the back contact and armature oi? the relay 311 to ground. The lamp 330 is lighted, and the operator at the private branch er-zchange makes her inquiry in the above described manner by connecting her telephone 3 to the trunk conductors 321. 32". through the key contacts l l hcn the flow of ringing current ceases, the relay 323 and, in turn, relay 312 beconic (lo-energized.

The private branch exchange operator actuates new key 333, indicating the group of the called subscriber, and the keys 34:0 and 341, indicating the tens and units digits, respectively, oi the called ni'un er. Due to the actuation of these keys, tl e fol owing circuits are closed; from ground through the Winding of the relay 380, the upper contact of key 333, and the left-hand contact of key 34-1 to grounded battery. The relay 330 hecomes energized and closes the following circuits; from ground through the winding of slow acting relay 302, and then in parallel through the Winding of relays 370 and 360., relay contacts 381 and 382, and the contacts of keys 340 and 341 to grounded battery. The relays 302, 360 and 370 become energized, and lock up through resistance 369 and 379 to grounded battery at the left-hand armature of the relay 309.

Assuming that the line is idle, the marginal test relay 303 pulls up through its high resistance right-hand Winding, and locks up through its lOW resistance le. h: l

Winding, protecting the line inst seizure. A circuit is now closed iroin ground, through the outer armature and back contact of the relay 301, the right-hand nature and front contact of the relay 303, the Winding of relay 3041, the back contact and armature of the relay 310, and the back contacts and arinatures of the relays 301 and 306 to grounded battery. The relay 304lcloses a circuit from grounded battery through its lower armature and front contact, the Winding of relay 305 to ground, and the lamp 331 to ground. The relay 305 completes the ringing circuit which may be traced from ground through the ringing current generator 320, the upper front con tact of the relay 30 1-, relay contacts 36% and 3741, the bell at the called station, relay contacts 362 and 372, tie lower armature and front contact of the relay 305, and the Winding of marginal ringing relay 310 grounded battery. The lighting of lamp 331 cafes to the operator that the called line is being rung. Through its iniddle armature and front contact. the relay 304 bridges the relay 323 across the trunk conductors 321, 322. The relay 323 becoincs energized.

When, in response to the ringing of his bell, the called subscriber removes the receiver from the hook, the resistance oi the last traced circuit is suhiciently reduced to permit the energizatlon of relay 310. The relay 3041 becomes (ls-energized new and 4:. In a telephone exchange system, a plurality ct lines, means including a switch for establishing a connecting circuit between said lines, switch controlling mechanisms, mes," s operative upon the initiation of the establishment of said circuit for connecting said mechanisms with the circuit, means for rendering said lines busy, means whereby said switching means is selectively operated in accordance with the adjustment of said controlling mechanisms, means operable upon the establishment of said circuit in connection with an idle line for disassociating said mechanisms from the circuit, and means responsive to the busy condition of lines for maintaining said mechanisms in association with said circuit.

In a telephone exchange system, a plurality of lines, a switching device for selecting one of said lines, means for rendering busy said lines, testing means. responsive to the busy or idle condition of said lines associated with said device, controlling means for said device, means whereby said switching device is selectively operated in accordance with the adjustment of said controlling means, means for controlling the operative association between said controlling means and said device, and means controlled by said testing means for operating said last mentioned means.

6. in a telephone exchange system, a plurality of lines, means tor rendering busy said lines, a switching device for selecting one oi said lines, testing means associatet with the said switching device, signalling means associated with said device, controlling means for said device, means for as sociating said controlling means with said device, means responsive to the operation of the said testing means for operating said last mentioned means, and means responsive to the operation of the testing means for op erating the said signaling means.

7. in a telephone exchange system, a plurality oi lines, a variably operable impulse sending? device associated with each line,

lity of sets of counting relays, a plua plum rality or" line switching relays, a plurality of connecting relays, means common to said lines for operating one of said connecting relays for operatively associating a certain set oi? counting relays with said switching relays, means controlled by the impulse sending device of the calling line for adjusting the counting relays in accordance with the numerical designation of the called line, means for rendering busy said lines, a test relay, means controlled by said set of countin relays for operating said switching rela to select and seize the called line, a circuit for operating the test relay depending on the idle or busy condition of the called line, a nd a circuit for said one of the said connecting relays controlled by said test relay.

8. In a telephone exchange system, a plurality of lines, means for rendering busy said lines, a selectively operable switching device, a controlling means for said device, a busy signaling apparatus, and a relay et fective to control the association of said controlling means with said switching device and to render operative said apparatus.

9. In a telephone exchange system, a plurality of lines, a plurality of tens and units line selecting relays, a switching relay common to said tens relays and a switching relay common to said units relays, a variably operable controlling means for said switching and selecting relays, means for rendering busy said lines, testing means and a busy tone apparatus associated with said selecting relays, and means under the joint control of the switching relay common to the units selecting relays and the said testing means for connecting the busy tone apparatus with the calling line.

10. In a telephone exchange system, a calling and a called line, means including a selectively operable switching device for interconnecting said lines, means for rendering busy said called line, testing means associated with said device, a busy signal.- ing apparatus, a controlling means for said switching device, a relay provided with contacts appertaining to said lines, apparatus, switching device, and controlling means, and means for actuating said relay to connect said controlling means to said device and said apparatus with the said calling line.

11.111 a telephone exchange system, a calling and a called line, means including a selectively operable switching device for interconnecting said lines, means for rendering busy said called line, a controlling means for said switching device, testing means associated with said device, a busy signaling apparatus, a relay operative to connect said controlling means with said device, and means under the joint control of the said relay and said device for associating said apparatus with the calling line.

12. In a telephone exchange system, calling and called lines, means for producing current impulses representing digits of called line numbers, a switch, means for operating said switch in accordance with impulses representing digits of said numbers for connecting with called lines, another switch for extending a calling line to said switch, restoring means for said switches, and means responsive to the production of the impulses representing a particular digit for restoring said last mentioned switch before the first switch has been operated to extend the connection to the called line.

13. In a telephone exchange system, calling and called lines, means for producing id. in a telephone :ichange system, a calling line, called lines, Witching means to" interconnecting; said calling line and certai of said called lines, other switching means, s for actuating said switching ineans upon the initiation call from said callline and for maintaining said switching means actuated if the called line any one of said certain lines, means for restoring said switching means it the called l 1 another of said lines and for extending he connection through said other switching means.

15. In a telephone exchange system, oluality of lines, me s for producinecurrent npulses representing digits 01 called line numbers, an electromagnetic switch op l accordance with said impulses B in Ho select a called inc, another elect *oinagnetic ch, automatic means for operating, said i switch to connect a calling line with id first mentio d switch in response to initiation oi a call, holding circuit. said switches, and a slow acting relay ing contacts in said circuits.

16. In a telephone exchange systsn, a plu ality of lines leading to subscribers sta- V a line switching relay for interconne ting said lines, a1. actuating and a hold ing circuit for said relay, a first relay coniinch to .d lines, a con tact of the first rclay in the holding circuit, a second relay common to said lines, a contact of said second relay in the holding circuit, a circuit for said first relay, and a contact of said second relay and a contact at the substation in said last mentioned circuit.

17. In a telephone exchange systen'i, a plurality of lines leading to subscribers statio is, a line switching relay for interconnecting said lines, an actuating and a hold ing circuit tor said relay, a first slow-actng relay common to said lines, a contact of the first relay in the holding Cli'Cll', a seconn slow-acting relay common to said lines, a contact of said second relay in the holding circuit, a circuit for said first relay, one a con act of said second relay and a contact the substation in said last mentioned circuit.

necting said lines, a relay for controlling the incense restoration of said switch, circuit for relay incluoing three contacts, ineans asso ciated with said switch for controlling i 01 said contacts, ineans f1SSO" -"L individual to the calling 7 another contact, 1

anc plurality o l said lines third contact.

19. In a telephone excl ing and called l" said switch to slow-actingtion of said s lay including tl two contacts and switch, means a"; the trolling one or sai l t common to a pli 90. In a ti; ?ality of line ing; in said c sonting digits oi llllpll i303 nonihc s, a slow L acting relay in a a s tch n'icrable in accordance with said lSQS fOl 96 selecting called line. anot tor connecting a L ch, holding circ ontacts 0t I hold rality oit tele necting circu't ing devices, so devices, inc/an, lines "for actnat of counting rel: 3 controlled by said count sting anodier one ti" on said devices and contacts on said said connecting circ 23. In a telephone c: rality of incoming and lay for each ten inc'iinii each ten out: d] l lays for in ten relays i sive to the i. i. coining line of I said second group, other contacts in said locking circuits, and means controlled by the elays of one of the groups for actuating said contacts.

29. ln combination, a circuit, an interrupting device at one end or said circuit, a controlling relay at the other end of said circuit responsive to certain operations of said device, two contacts for said relay, tWo groups of relays, actuating circuits for the relays one group through one contact of the controlling relay and contacts of an active and inactive relays of the other group, and actuating circuits for the relays of the other groups through the other contact of the controlling relay and contacts of an active and inactive relays 01" said one group.

. ln combination, a circuit, an interrupting device at one end of said circuit, a conthe other end of said cirrow and a heel: contact for said two groups of serially arranged reays, s "ccessive actuaing circuits for the reays ii one group through the front contact of the controlling relay, the bacl: contacts oi inactive relays and the front contact of an active relay oil the second group, a locking circuit for the relays of said one group, successive actuating circuits for the relays *roup through the back con- .olling relay, the front con ctive relay and the back con- ,ctive relays or said one group, q circuit for the relays of said second group i ln combination, slow acting controllug relay, a second controlling relay, an ine rupting device in circuit With said reys, said slow relay responding only to cerain operations of said interrupting device, *roups ct serially arranged relays, succcssire actuating circuits for the relays of one 3 through a contact of the second controll relay, the contact of an inactive relay and the contact of an active relay of the econd group, successive actuating circuits tor the relays of the second group through another contact of said second controlling relay, the contact of an inactive relay the contact oi an active relay of one group, locking circuits for the relays of said groups, and a contact on said slow acting controlling relay common to said loclrino' circuits.

32. in combination, a group of a relays pro ed with contacts, a second group of t relays provided with contacts, the energizing circuit of the first relay of the first group being connected to a back contact of the lay of said second group, the respective energizing circuits of the remaining relays of the first group being connected in order {0 front contacts of the relays of said second group, and the respective energizing circuits or the relays of said second group being connected in order to front contacts of the first n relays of the first group.

83. in combination, a circuit, interrupting device arranged to produce impulses a; one end of said circuit, a first controlling relay and a second controlling relay resiiionsive to impulses the other end or the circuit, a first, a second, a third and a fourth group oi? relays, contacts ifor all oi': sa d relays, actuating circui"s tor the vela t; the first group throughv a contact or first controlling relay and centre active and active relays oi? the second actuating circuits 'for the relays of the second group through another con f the first controlling relay and cont 1%? inactive and active relays oi: the rroup, actuating circuits for the relays thirc group through a contact of the c I controlling relay and contacts of inactive and of active relays of the fourth group, and actuating circuits for the relays in the fourth group through anoticr contact o1 the second controlling rel y and contacts oi inctive and active relays of the third groi-ip.

in combination, a circuit, an interruptdevice arranged to produce inipulr-ies of short and long duration at one end of said circuit, a first controlling relay responsive to all impulses and second controlling re lay responsive only to the long impulses at the other end the circuit, a. bi: ich for said circuit including a sloWto-1.'elease relay, a first, a second a third and a fourth group of serially arr cd relays, contacts for all 01' said relays, actuating c rcuits tor the relays of the first group through the front contact of the controlling relay, the back contacts of the inactive and the front contact of an active relay of the second group, locking circuits for the relays of the first group through the front contact of an active and the back contacts of the inactive relays ot the first group and the front contact of the sl vv-torelease relay, actuating circuits for the relays of the second group through the hack contact the first controlling relay, the heel: contacts of inactive and the front contact of an active relay of the first group, locking circuits for the relays oi": the second group through the front contact ct an active, the back contacts of inactive renys of the second group and the front contact of the sloW-to-release relay, actuating circuits tor the relays of the third group through the front contact of the second controlling lay, the back contacts or inactive and the front contacts of active relays oi the fourth group, actuating circuits for the relays of the fourth group through the back contact of the second controlling relay, bacl: contacts of inactive and front contacts of active relays of the third group, locking circuits for the relays of the third and fourth groups 

